A voltage stabilizer is known in the related art. It is usually used, modified in various ways. The voltage stabilizer has additional smoothing and control elements depending on the demands made on it.
Voltage-supply devices for motor vehicles, in particular, require a special design. The vehicle voltage system already fluctuates within wide limits depending on whether the vehicle battery is charged or discharged, whether the vehicle engine is running or not, whether the ambient temperature is low or high, or whether there is sufficient battery fluid in the battery.
Furthermore, it may be necessary to compensate for considerable voltage jumps which occur when a low-resistance load such as the engine starter, the rear defroster or the high beams are switched on or off. A multitude of voltage peaks of different leading edge and different amplitude, which can be caused by ignition processes or the switching of capacitive or inductive loads, can also be superimposed on the supply voltage.
For the voltage supply of electronic loads in motor vehicles, a voltage-supply device is known which furnishes a load voltage that lies below the supply voltage, but is limited to a specifiable maximum value such as 9 volt or 12 volt. This load voltage is not stabilized; however voltage jumps in response to load changes are compensated. Furthermore, by means of the known voltage-supply device, a second load voltage is generated which is stabilized to a fixed, specifiable value and in the case of which, all load changes are compensated very quickly. Both load voltages are generated by means of an in-phase regulator connected between the supply-voltage input and the respective load-voltage output.
Achieved by special circuitry measures is that, given small supply voltages at the in-phase regulator, a small voltage drop occurs.
Disadvantageous in the last-named voltage-supply device, but also in the case of all other known voltage-supply devices which have an in-phase regulator connected between the supply-voltage input and the load-voltage output, is that the excess voltage drops off at the in-phase regulator, which means a relatively large power loss occurs at the in-phase regulator. The dissipation power is completely converted into heat which heats the voltage-supply device in an unwanted manner. This is very disadvantageous particularly in the case of voltage stabilizers constructed using hybrid technology, since due to this, the output power of the voltage stabilizers is limited.
Therefore, given voltage stabilizers of great power, it is necessary to resort to costly measures to dissipate the power-loss heat. In addition, subject to the power loss, the electric circuit must not fall below a certain size.
An object of the present invention is to design a voltage stabilizer in such a way that, given great output power, the design of the electric circuit can be kept small.